remains unchanged the two outer angles of each of the more or 

 less quadrate lips are dravm out into extended lobes. Fig. 23. 

 At the same time the pillars of the proboscis thicken and the 

 jelly is continued outward along each of these lobes as a mid- 

 rib. We have then eight oral arms each with a longitudinal 

 groove, supported by a midrib aiid fringed with digitella ; 

 arms very similar to those characteristic of the genus Aurcsa, 

 Haeckel (1879). But it is only the mouth pai'ts of Oassiopea 

 that may be said to pass through an A^rosa stage, for the oam- 

 parison cannot, at this time at least, be carried to the other 

 organs. As the gelatinous axes of the oral arms are thicken- 

 ed, their bases unite to form the oral disk. 



Glaus has described (1883) some of the principal stages 

 in the metamorphosis of Pilema (Rhizostoma) and Cotylorhiza. 

 He re^rds the formation of the eight oral arms as a different 

 process in these forms from what occurs in Aurcsa. There it 

 is a splitting of the four oral arms, here it is an outgrowth 

 of the corners of the ephyrula lips. This sounds to me like 

 the sar:^e thing merely expressed in two different ways. the 

 comparison that Glaus makes between the process of formation 

 of the eight arms and the foldings of these arms that results 

 in the oscula seems hardly applicable in Cassiopea, as will ap- 



